1. Field of the Invention
The present invention relates to a keypad assembly having reflection pattern.
2. Description of the Related Art
Generally, a keypad assembly of the conventional portable terminal includes a keypad. A keypad assembly may have a switch substrate. The keypad includes a plate-shaped elastic layer and a plurality of key buttons formed on a first surface of the elastic layer. In the keypad, characters and the like are respectively printed on each surface of the key button. The switch substrate on which a plurality of switches is integrated to provide electric contact as the respective key button is pushed, resulting in converting a press to the respective key button into electric signal.
A portable terminal has lighting elements for a user to use the keypad even in the dark. A plurality of light emitting diodes and inorganic electro luminescence are used as the lighting elements. The light emitting diodes are generally arranged on a printed circuit board, while the inorganic electro luminescence is inserted in an elastic pad.
FIG. 1 is a sectional view showing a keypad assembly 100 including a plurality of light emitting diodes according to the conventional art. Referring to FIG. 1, the conventional keypad assembly 100 includes a switch substrate 120, a plurality of diodes 122 and a keypad 110.
The keypad 110 includes a plate-shaped elastic layer 111, a plurality of key buttons 112 formed on a first surface of the elastic layer 111 and on each of which characters and the like are printed, and a plurality of protrusions 111a formed on a second surface of the elastic layer 111 opposite to the first surface. Each key button 112 and the corresponding protrusion 111a are aligned vertically.
The switch substrate 120 includes a plate type printed circuit board 120a and a plurality of switches 121 formed on an upper surface of the printed circuit board 120a while being opposed to the keypad 110. Each switch 121 includes a conductive contact member and a conductive dome fully covering the contact member. The light emitting diodes 122 are mounted on the upper surface of the printed circuit board 120a. 
Each light emitting diode 122 is preferably prevented from being located in vertical alignment with a corresponding key button 112, in order to ensure operation of the switch 121. That is, the light emitting diodes 122 are respectively placed between the switches 121, so as to emit the light to the respective key buttons 112 at an oblique angle. The emitted light may unevenly reach each key button 112. Therefore, the respective key buttons may be shaded in darkness.
Therefore, a keypad assembly was proposed which includes a keypad having an elastic layer and inorganic electro luminescence inserted in the elastic layer. However, a separate AC electric source is necessary in order to use the inorganic electro luminescence. That is, the keypad assembly including the inorganic luminescence may have an inverter in order to convert DC to AC. As a result, a volume and a manufacturing cost of the keypad assembly may increase. In addition, DC to AC conversion may generate noise in the portable terminal.